The invention relates to improvements in methods of and in apparatus for applying flowable substances to running webs or strips of wrapping material in rod making machines, especially in rod making machines of the tobacco processing industry. Typical examples of such machines are so-called filter rod making machines which serve to make continuous rods of wrapped filter material for tobacco smoke. The rod is subdivided into filter rod sections of unit length or multiple unit length which can be fed to a so-called tipping machine wherein the filter rod sections are assembled with cigarette-, cigar- or cigarillo rod sections to form therewith filter cigarettes, cigars or cigarillos of unit length or multiple unit length.
Filter rod making machines are disclosed, for example, in U.S. Pat. No. 3,974,007 granted Aug. 10, 1976 to Greve for “METHOD AND APPARATUS FOR THE PRODUCTION OF FILTER ROD SECTIONS OR THE LIKE”, and in U.S. Pat. No. 4,412,505 granted Nov. 1, 1983 to Häusler et al. for “APPARATUS FOR APPLYING ATOMIZED LIQUID TO A RUNNING LAYER OF FILAMENTARY MATERIAL OR THE LIKE”. A filter tipping machine is disclosed, for example, in U.S. Pat. No. 5,135,008 granted Aug. 4, 1992 to Oesterling et al. for “METHOD OF AND APPARATUS FOR MAKING FILTER CIGARETTES”.
Recent versions of apparatus for applying adhesive to running webs of wrapping material in filter rod making machines are constructed in such a way that one side of the running web of wrapping material for a rod-like filler of filter material (such as acetate fibers) for tobacco smoke is provided with two longitudinally extending films or layers or other accumulations of adhesive material, namely a first layer which is used to bond the overlapping marginal portions of the web to each other subsequent to draping of the web around successive increments of the running web around the filler, and a second layer which serves to bond the internal surface of the converted (tubular) web to the confined filler. Draping of the web around the rod-like filler is carried out in a wrapping apparatus which normally employs an endless belt (called garniture) serving to convert a running flat web or strip of cigarette paper or the like into a tubular envelope surrounding the filler. Adhesive applying apparatus of the just outlined character are disclosed, for example, in German patent application Serial No. 31 43 526 A of Vaughan (published Jun. 9, 1982) and in British patent No. 1 305 023 granted Jan. 31, 1973 to Molins Machine Company Limited.
A drawback of the conventional adhesive applying methods and apparatus is that the adhesive substance often penetrates through the web of wrapping material and contaminates those portions of a filter rod making or filter tipping machine which come into contact with the adhesive. Moreover, the adhesive at the outer side of the tubular envelope affects the appearance of the filter cigarette, cigar or cigarillo and renders it necessary to segregate such smokers' products from acceptable smokers' products.
The likelihood of penetration of adhesive (such as a hotmelt) through the web is especially pronounced if the adhesive is applied to one side of a foraminous web, e.g., a web which has been perforated on purpose in order to permit atmospheric air to penetrate into the mouthpiece of a filter cigarette or the like and to mix with tobacco smoke flowing from the lighted end of a filter cigarette or the like into the mouth of a smoker. Apparatus which can be utilized to perforate the webs of wrapping material for rod-shaped cigarette fillers or filter rod fillers are disclosed, for example, in U.S. Pat. No. 4,281,670 granted Aug. 4, 1981 to Heitmann et al. for “APPARATUS FOR INCREASING THE PERMEABILITY OF WRAPPING MATERIAL FOR ROD-SHAPED SMOKERS' PRODUCTS”, and in U.S. Pat. No. 4,889,140 granted Dec. 26, 1989 to Lorenzen et al. for “APPARATUS FOR MAKING PERFORATIONS IN ARTICLES OF THE TOBACCO PROCESSING INDUSTRY”.
In fact, an adhesive substance which has been applied to one marginal portion of a running web of cigarette paper in a cigarette rod making machine is likely to penetrate through the tubular envelope of the plain cigarette as well as through the tubular envelope which is made of so-called tipping paper and serves to connect a plain cigarette with a filter mouthpiece, e.g., in a manner as disclosed, for example, in the aforementioned U.S. Pat. No. 5,125,008 to Oesterling et al. The adhesive which has penetrated through the cigarette paper as well as through the tipping paper is likely to contaminate the tipping machine and to necessitate segregation of numerous filter cigarettes between the maker of such products and the packing machine.